Make sure your noitem config looks like this.
Notify:
Admins: false
AdminMessage: '&e%n &9tried to &c%t %i &9in world %w @ &a%x,%y,%z'
NoUse: true
NoUseMessage: '&9You are not allowed to use a(n) &4%i&9!'
NoBrew: true
NoBrewMessage: 'You are not allowed to brew that potion! &4(%i)'
NoHold: true
NoHoldMessage: 'You are not allowed to hold &4%i&9!'
NoWear: true
NoWearMessage: 'You are not allowed to wear &4%i&9!'
NoCraft: true
NoCraftMessage: 'You are not allowed to craft &4%i&9.'
NoPickup: true
NoPickupMessage: 'You are not allowed to pick that up! (%i)'
NoCook: true
NoCookMessage: 'You are not allowed to cook &4%i&9.'
NoDrop: true
NoDropMessage: 'You are not allowed to drop &4%i.'
NoBreak: true
NoBreakMessage: 'You are not allowed to break &4%i.'
NoPlace: true
NoPlaceMessage: 'You are not allowed to place &4%i.'
I have quantum chest plate banned and it works fine for me people cannot wear it
also I found with pex its better to put permissions in order so try putiing all the noitem permissions first the the rest of your other permissions.
- noitem.nowear.x30173.1
- noitem.nowear.x30173.27